Post on 05-Feb-2016
description
Overexpression of MMP9 in colonic epithelium mediates protection in colitis associated cancer
PALLAVI GARG Ph.D.
Disclosures
Nothing to Disclose
Matrix Metalloproteinases (MMPs)
Are a family of zinc-dependent proteolytic
enzymes with the ability to degrade extracellular matrix substrates such as
collagen, gelatin and proteoglycans
Colitis Associated Cancer (CAC) & Colorectal Cancer• CAC is an important complication of Ulcerative Colitis or colonic Crohn’s Disease
that results in significant morbidity and mortality
• It causes 1/6 of all deaths in patients with ulcerative colitis
• Colon cancer develops in flat dysplastic tissue among IBD individuals
• CAC is often multiple, anaplastic, broadly infiltrating, rapidly growing and occurs at a younger age
• The pathogenesis of CAC is not known
MMP9 and its role in acute colitis
•MMP9 is not expressed in normal tissues and is one of the predominant MMPs that is up-regulated in several animal models of colitis and human IBD
•MMP9 mRNA and protein levels are increased in the inflamed colonic mucosa of patients with IBD
•MMP9 activity correlates with active inflammation
•MMP9 activates Notch1 signaling in colonic epithelium
Castaneda et al, 2005, GastroenterologyGarg et al, 2007, Gastroenterology
Role of MMP9 in CAC
• MMP9-/- mice show increased susceptibility to CAC
• CAC in MMP9-/- mice is associated with decreased apoptosis compared to WT mice
• CAC in MMP9-/- mice showed decreased levels of p21WAF1/Cip1
and p53
• MMP9 mediates its tumor suppressive role via activation of Notch1 signaling
Garg et al, 2010, Cancer ResearchGarg et al, 2011, Gastroenterology
Which MMP9 protects from CAC ?
Aim
In vivo model
C57/B6
WT Tg-villin-MMP9
Water
Water
DSS (3 cycles)
DSS= Dextran Sodium Sulfate (3% in drinking water)
DSS (3 cycles)
In vivo protocol
0Days
49 7 14 28 35
DSS Cycle (1st) starts
DSS Cycle(2nd ) starts
Recovery(1st) starts
Recovery(2nd) starts
DSS Cycle(3rd ) starts
Recovery(3rd) starts
53 85
sacrifice
* *
*B
ody
wei
ght g
ain
in p
erce
ntag
e
DSS cycle 1
Recovery cycle 1
DSS cycle 2
Recovery cycle 2
SacrificeDSS cycle 3
Recovery cycle 3
1 2 3
Tg-villin-MMP9WT
*
A B
WT CAC
Tg-villin-MMP9 CAC
Num
ber
of d
yspl
asti
c le
sion
s
Num
ber
of p
olyp
s
WT CAC
Tg-villin-MMP9 CAC
*
X10 X20
WT CAC
Tg-villin-MMP9 CAC
MMP9, 104 kD
β-tubulin
A
B NICD, 80 kD
β-tubulin
p53, 53 kD
GAPDH
C
WT, CAC
Tg-villin-MMP9, CAC
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6
WT, CAC
Tg-villin-MMP9, CAC
WT, CAC
Tg-villin-MMP9, CAC
Bax-1, 37 kD
p21WAF1/Cip1, 21kDA
B
1 2 3 4 5 6
WT, CAC
Tg-villin-MMP9, CAC
WT, CAC
Tg-villin-MMP9, CAC
GAPDH
GAPDH1 2 3 4 5 6
Overexpression of MMP9 in MMP9-/- MEFs showed increased levels of Notch1 and p53
MMP-9, 104 kD
MMP9-/- MEFs
WT MEFs
A
B NICD, 80 kD
1 2 3 4 5 6
p53, 53 kDC
GAPDH
1 2 3 4 5 6
MMP9-/-MEFs + MMP9
GAPDH
MMP9-/- MEFs
WT MEFs
MMP9-/-MEFs + MMP9
•Epithelial-derived MMP9 plays a tumor suppressive role in CAC
• Overexpression of MMP9 in colonic epithelium is associated with altered levels of p53, Notch1, Bax1 and p21WAF1/Cip1
• Overexpression of MMP9 in MMP9-/-exhibited increased levels of NICD and p53
Summary
Inflammation
cytosol
nucleus
MMP-9
+
Notch-1 +
ARF
+ARFMdm2
Mdm2
+
p53+
Molecular mechanism of p53 regulation by MMP9 via Notch1
Mdm2
-
Conclusions
• Despite being a mediator of acute inflammation, epithelial derived- MMP9 acts as a tumor suppressor in CAC
• MMP9 mediated p53 activation via Notch1 signaling is necessary and sufficient for its tumor suppressive effect in CAC
Acknowledgement
Didier Merlin Lewins Walter
Crohn’s & Colitis Foundation of AmericaCareer Development Award, (#3057)